Lifting jack



March 16', 1926. 1,576,721

E. W. CONRAD LIFTING JACK Filed August 21, 1925 INVENTOR.

WCoIuvgcl, BY m'q ZA/L A TToRA/EYS.

Patented Mar. 16, 1926.

naar. w. conm, or wAnsAw, INDIANA.

LIFTING JACK.

Application led August 21, 1925. Serial No. 51,588.

To all whom 'it may concern.'

Be it known that I, EARL W. CONRAD, a citizen of the United States, residing at lVarsaw, in the county of Kosciusko and State of Indiana, have invented new and useful Improvements in Lifting' Jacks, of which the following is a specification.

The invention relates to jacks and its object is to provide an eilicient, durable, substantial and rapidly operating jack.

The invention consists in the, novel combination and arrangement of parts hereinafter described and illustrated in the drawings, in which drawings- Figure 1 is a side elevational View of a device embodying the invention; Fig. 2 a plan view of the same; Fig. 3 an end view of the same and Fig. 4 a detail view of the thrust bearing for the screw.

Referring to the illustrative embodiment of the invention, 1 is the 'base having onv its upper side-two pairs of lugs 2, 2 and 3,`

the other lug of the pair 3 not being shown.

The members of each pair are spaced transversely and the pairs are properly spaced from each other lengthwise of the base. Two links 4, 4 are pivoted at their lower 4 ends to the lugs 2, 2 respectively. The

)looted et its oppOBte upper ends of the links 4, 4 are loosely mounted on the pins lor spindles 6, 6 which project from the opposite ends of a collar 7. Links 10 are loosely mounted at their upper ends upon the pins or spindles 8, 8 and their lower ends are pivoted at a selected point to the links 4, 4 respectively.` Two links 11, 11 are loosely mounted on the pins orspindles 6, 6 respectively and the two links 12, 12 are loosely mounted on the pins or spindles 8, -8" respectively. The link 11 is pivoted to the link 12 Yand the link 11 is pllvoted to the link 12 by a bolt 13, upon whic bolt there is an enlarged portion 14, which spaces one pair ofthe crossed links from the other. Cotter pins 15 are secured in the pins or spindles to retainl the severed links thereon.

The upperends of the links 11, 11'- are loosely connected by a bolt 16 upon which bolt and between thel-inks a roller 17 is mounted and a similar Abolt 18 loosely con nects the links 12, 12 and a roller 19 is similarly mounted on this bolt 1 8. .Ai dshed late 20, havingV its opposite ends curved ownwardly rests upon the rollers 17 and 19 and a. coiled sparing, 21 is conen to the lowerlower ends tothe lugs ends of the plate l19. The spring extends under the enlarged portion 14 of the pivot bOlt 13.

A central opening 22 'is formed in the collar 9 through which is loosely projected a screw 23. The screw also threads through the sleeve 7. A housing 24 is suitably secured to the outer face of the collar 9 and the `screw 23 is projected through 1t. A cone 25 is formed on the screw and cooperates withthe inner wall balls 26, the balls being held in the race bya spring washer 27 that is sprung in a groove 28 formed in the wall of the housing. The forward end 29 of the screw is properly formed to receive a wrench or other device by which to rotate the, screw.

A pin or rivet 30 is inserted through the screw adjacent to the rear end of the collar 9 and a washer 31 is placed between the collar and thepin.

The ball bearing forms a4 very elicient thrust bearing for the screw and enables easy rotation of the screw..y Since the screw isloose in the collar 9.1and the pin 30 prevents longitudinal movement lof the collar on the screw, and the collar 7 is threaded on the screw, it is evident that when the screw is rotated the collar 7 must travel on the screw either way from or toward the collar 9 depending upon the direction of` rotation of. the screw.

In Fig. 1, as shown in broken lines, the screw has been rotated to the'right (Fig. 3). The traveling collar 7 has moved ward the collar 9. The pivoted links therefore, move toward an erect position and elevate the plate 20, the links 10 forming a brace to-steady the structure and preventing the collapse or ti ping over 4the same.

-Since the Ilate 20 is loose1y'"`engaged on the. rollers 17) and 19 by the tension of the spring 21 it readily accommodates expanding and contracting movement of the upper ends of the up er links. At the same time an object un er which the late is engaged will seek the lowest part o the bow and hence will not .disengage from atlclaim is:

on the base, crossing s pivoted at their lars pivotally connected to the-upper endl f the 1mb,

o links pivotally y connected to' comprising a. base, lugs` respectively, two co1-A Iof the housing to form a ball race for the one of the collars andalso to two of the crossing links, crossing links ivotally connected at their lower ends to t e collars and being pivoted together at their crossing i points, transverse rollers connecting the upper ends of the last named links, 'a plate contacting with the rollers, a spring resiliently retaining the plate on said rollers, a .thrust bearing formed on one of the collars 4and a screw revolubly mounted in the latter collar and bearing and in threaded engagementwith the other collar.

2. A lifting jack comprising a base, lugs on the base,'crossing links pivoted at their other pair of said links, a pair of links pivotally connected to one of said members and to the pair of crossing links that is connectedl to the other member, crossing links pivotally connected at their lower ends to Said links being pivoted together at their crossing points, a. roller between the upper ends of each pair of the latter links, a plate slidably engaged on the rollers and a spring engaged to the opposite ends of the plate, also enga ed under the pivot connecting the latter lin s at their crossing points, and a screw revolubly mounted 1n the bearing member and in threaded engagement with the collar member.

In witness whereof I have hereunto set my hand this 17th day of August 1925.

. EARL w. CONRAD. 

